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High speed error correction for continuous-variable quantum key distribution with multi-edge type LDPC code

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arXiv 2017年

作者： Wang, Xiangyu Zhang, Yichen Yu, Song Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Center for Quantum Information Technology Center for Computational Science and Engineering Peking University Beijing100871 China

Error correction is a significant step in postprocessing of continuous-variable quantum key distribution system, which is used to make two distant legitimate parties share identical corrected keys. We propose an experiment demonstration of high speed error correction with multi-edge type low-density parity check (MET-LDPC) codes based on graphic processing unit (GPU). GPU supports to calculate the messages of MET-LDPC codes simultaneously and decode multiple codewords in parallel. We optimize the memory structure of parity check matrix and the belief propagation decoding algorithm to reduce computational complexity. Our results show that GPU-based decoding algorithm greatly improves the error correction speed. For the three typical code rate, i.e., 0.1, 0.05 and 0.02, when the block length is 106 and the iteration number are 100, 150 and 200, the average error correction speed can be respectively achieved to 30.39Mbits/s (over three times faster than previous demonstrations), 21.23Mbits/s and 16.41Mbits/s with 64 codewords decoding in parallel, which supports high-speed real-time continuous-variable quantum key distribution system. Copyright © 2017, The Authors. All rights reserved.

关键词： Matrix algebra

Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

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arXiv 2017年

作者： Zhao, Yijia Zhang, Yichen Yu, Song Li, Zhengyu Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China State Key Laboratory of Advanced Optical Communication Systems and Networks Center for Computational Science and Engineering Center for Quantum Information Technology School of Electronics Engineering and Computer Science Peking University Beijing100871 China

We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The Virtual photon subtraction implemented via non-Gaussian postselection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase of distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum cryptography

Finite-size analysis of continuous-variable measurement-device-independent quantum key distribution

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arXiv 2017年

作者： Zhang, Xueying Zhang, Yichen Zhao, Yijia Wang, Xiangyu Yu, Song Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Center for Quantum Information Technology Center for Computational Science and Engineering Peking University Beijing100871 China

We study the impact of the finite-size effect on the continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocol, mainly considering the finite-size effect on the parameter estimation procedure. The central-limit theorem and maximum likelihood estimation theorem are used to estimate the parameters. We also analyze the relationship between the number of exchanged signals and the optimal modulation variance in the protocol. It is proved that when Charlie’s position is close to Bob, the CV-MDI QKD protocol has the farthest transmission distance in the finite-size scenario. Finally, we discuss the impact of finite-size effects related to the practical detection in the CV-MDI QKD protocol. The overall results indicate that the finite-size effect has a great influence on the secret key rate of the CV-MDI QKD protocol and should not be ignored. Copyright © 2017, The Authors. All rights reserved.

关键词： Parameter estimation

On the impact of antenna patterns on VANET simulation

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On the impact of antenna patterns on VANET simulation

IEEE Vehicular Networking Conference (VNC)

作者： David Eckhoff Alexander Brummer Christoph Sommer Computer Networks and Communication Systems University of Erlangen Germany Dept. of Computer Science Paderborn University Germany

ISBN: (纸本)9781509051984

Although the level of realism in vehicular network simulation is constantly increasing, antenna radiation patterns have only rarely entered the picture. In this paper we investigate the impact of these antenna patterns on the outcome of a city-wide simulation with hundreds of cars as well as an isolated intersection collision avoidance scenario. We show that in both cases pronounced differences can be observed: Compared to idealistic isotropic antennas, using realistic antennas changes the distribution of angle of arrival, affecting network topology dynamics. In collision avoidance applications, the antenna radiation pattern can make the difference between a crash and a successful emergency brake, strongly indicating that antenna characteristics should find more consideration in vehicular network simulation.

关键词： Antenna radiation patterns Vehicles Receiving antennas Safety Computational modeling Antenna measurements

High speed continuous variable source-independent quantum random number generation

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arXiv 2017年

作者： Xu, Bingjie Chen, Ziyang Li, Zhengyu Yang, Jie Su, Qi Huang, Wei Zhang, Yichen Guo, Hong Science and Technology on Security Communication Laboratory Institute of Southwestern Communication Chengdu610041 China State Key Laboratory of Cryptography Beijing100878 China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Center for Quantum Information Technology Peking University Beijing100871 China State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China

As a fundamental phenomenon in nature, randomness has a wide range of applications in the fields of science and engineering. Among different types of randomnumber generators (RNG), quantumrandomnumber generator (QRNG) is a kind of promising RNG as it can provide provable true randomnumbers based on the inherent randomness of fundamental quantum processes. Nevertheless, the randomness from a QRNG can be diminished (or even destroyed) if the devices (especially the entropy source devices) are not perfect or ill-characterized. To eliminate the practical security loopholes from the source, sourceindependentQRNGs, which allow the source to have arbitrary and unknown dimensions, have been introduced and become one of the most important semi-device-independent QRNGs. Herein a method that enables ultra-fast unpredictable quantum random number generation from quadrature fluctuations of quantum optical field without any assumptions on the input states is proposed. Particularly, to estimate a lower bound on the extractable randomness that is independent from side information held by an eavesdropper, a new security analysis framework is established based on the extremality of Gaussian states, which can be easily extended to design and analyze new semi-device-independent continuous variable QRNG protocols. Moreover, the practical imperfections of the QRNG including the effects of excess noise, finite sampling range, finite resolution and asymmetric conjugate quadratures are taken into account and quantitatively analyzed. Finally, the proposed method is experimentally demonstrated to obtain high secure randomnumber generation rates of 15.07Gbits/s in off-line configuration and can potentially achieve 6 Gbits/s by real-time post-processing. Copyright © 2017, arXiv, All rights reserved.

关键词： Random processes

On the secrecy capacity of fisher-snedecor f fading channels

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arXiv 2018年

作者： Badarneh, Osamah S. Sofotasios, Paschalis C. Muhaidat, Sami Cotton, Simon L. Rabie, Khaled Al-Dhahir, Naofal Department of Electrical Engineering University of Tabuk P. O. Box 741 Tabuk Saudi Arabia Department of Electrical and Computer Engineering Khalifa University of Science and Technology P. O. Box 127788 Abu Dhabi United Arab Emirates Department of Electronics and Communications Engineering Tampere University of Technology TampereFI-33101 Finland Institute for Communication Systems University of Surrey GuildfordGU2 7XH United Kingdom Institute of Electronics Communications and Information Technology Queen's University Belfast BelfastBT3 9DT United Kingdom School of Electrical Engineering Manchester Metropolitan University ManchesterM15 6BH United Kingdom Department of Electrical and Computer Engineering University of Texas at Dallas RichardsonTX75080 United States

The performance of physical-layer security of the classic Wyner's wiretap model over Fisher-Snedecor F composite fading channels is considered in this work. Specifically, the main channel (i.e., between the source and the legitimate destination) and the eavesdropper's channel (i.e., between the source and the illegitimate destination) are assumed to experience independent quasi-static Fisher-Snedecor F fading conditions, which have been shown to be encountered in realistic wireless transmission scenarios in conventional and emerging communication systems. In this context, exact closed-form expressions for the average secrecy capacity (ASC) and the probability of non-zero secrecy capacity (PNSC) are derived. Additionally, an asymptotic analytical expression for the ASC is also presented. The impact of shadowing and multipath fading on the secrecy performance is investigated. Our results show that increasing the fading parameter of the main channel and/or the shadowing parameter of the eavesdropper's channel improves the secrecy performance. The analytical results are compared with Monte-Carlo simulations to validate the analysis. Copyright © 2018, arXiv, All rights reserved.

关键词： Fading channels

Efficient rate-adaptive reconciliation for continuous-variable quantum key distribution

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arXiv 2017年

作者： Wang, Xiangyu Zhang, Yichen Yu, Song Bingjie, X.U. Li, Zhengyu Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications No. 10 Xitucheng Road Beijing100876 China Science and Technology on Communication Security Laboratory Institute of Southwestern Communication No. 6 Chuangye Road Chengdu610041 China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Center for Quantum Information Technology Center for Computational Science and Engineering Peking University No. 5 Yiheyuan Road Beijing100871 China

Information reconciliation protocol has a significant effect on the secret key rate and maximal transmission distance of continuous-variable quantum key distribution (CV-QKD) systems. We propose an efficient rate-adaptive reconciliation protocol suitable for practical CV-QKD systems with time-varying quantum channel. This protocol changes the code rate of multi-edge type low density parity check codes, by puncturing (increasing the code rate) and shortening (decreasing the code rate) techniques, to enlarge the correctable signal-to-noise ratios regime, thus improves the overall reconciliation efficiency comparing to the original fixed rate reconciliation protocol. We verify our rate-adaptive reconciliation protocol with three typical code rate, i.e., 0.1, 0.05 and 0.02, the reconciliation efficiency keep around 93.5%, 95.4% and 96.4% for different signal-to-noise ratios, which shows the potential of implementing high-performance CV-QKD systems using single code rate matrix. Copyright © 2017, The Authors. All rights reserved.

关键词： Efficiency

Jitter floor elimination for blind feedforward/feedback symbol-timing recovery exploiting the extended zero-crossing property

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Jitter floor elimination for blind feedforward/feedback symb...

作者： Gappmair, Wilfried Cioni, Stefano Corazza, Giovanni E. Koudelka, Otto Institute of Communication Networks and Satellite Communications Graz University of Technology Graz Austria European Space Agency ESA/ESTEC Noordwijk Noordwijk Netherlands Department of Electronics Computer Science and Systems University of Bologna Bologna Italy

Carrier-blind and non-data-aided recovery of the symbol timing is of paramount importance in digital receivers, that is, detailed knowledge about carrier frequency and phase or any pilot sequence is not necessary for proper operation. In this context, feedforward algorithms are particularly helpful in packet-oriented systems, where rapid and stable acquisition of the major transmission parameters is essential for subsequent processing stages. On the other hand, feedback algorithms are typically used to track small deviations from the stable equilibrium point. In the current paper, we propose a new approach for blind feedforward and feedback recovery of the symbol timing, which needs just one or two samples per symbol. The method is characterized by a second filter operated in parallel to the receiver-matched filter. Under Nyquist conditions, exemplified by baseband pulses having a square-root raised cosine spectrum, this filter exhibits an impulse response satisfying the extended zero-crossing property, that is, it vanishes for all integer multiples of the symbol period including the origin. Using this idea for symbol-timing recovery, it is shown that the annoying jitter floor – typical for most timing recovery schemes and caused by inter-symbol interference – can be avoided irrespective of the selected modulation scheme. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

关键词： Floors

Index modulation for 5G: Striving to do more with less

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arXiv 2017年

作者： Cheng, Xiang Zhang, Meng Wen, Miaowen Yang, Liuqing State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics and Computer Science Peking University Beijing100871 China State Key Laboratory of Integrated Services Networks Xidian University Xi'an710000 China China Telecom Technology Innovation Center Beijing102209 China School of Electronic and Information Engineering South China University of Technology Guangzhou510640 China Department of Electrical and Computer Engineering Colorado State University Fort CollinsCO80523 United States

The fifth generation (5G) wireless communications brag both high spectrum efficiency and high energy efficiency. To meet the requirements, various new techniques have been proposed. Among these, the recently-emerging index modulation has attracted significant interests. By judiciously activating a subset of certain communication building blocks, such as antenna, subcarrier and time slot, index modulation is claimed to have the potential to meet the challenging 5G needs. In this article, we will discuss index modulation and its general and specific representations, enhancements, and potential applications in various 5G scenarios. The objective is to reveal whether, and how, index modulation may strive for more performance gains with less medium resource occupation. Copyright © 2017, The Authors. All rights reserved.

关键词： Orthogonal frequency division multiplexing